RCU Forums - Custom 1/5 Scale Monster Build Report

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Custom 1/5 Scale Monster Build Report

Been working on this fora while now, but been busy with school and other hobbies so it got put on the back burner. However, with school ending in two weeks, and a shop at my disposal, we're having some fun this summer! Most of the manual parts will be made by me, and most of the cnc'd parts will be made by generous friends!

It's a several phase project, eventually ending up full autonomous (although I'm not letting this impact the normal performance), but starting out as just a badaass 1/5 scale Monster.

Working on suspension arms, wheelknuckles and shafts now.

Here are so teaser pics in the meantime!

RE: Custom 1/5 Scale Monster Build Report

Those are some gorgeous parts! I'm look forward to seeing more.

RE: Custom 1/5 Scale Monster Build Report

I had already purchased a full set of rampage Mt tires, but was just ever so slightly dissapointed with their size. The wheelbase and trackwidth on mine are a few inches larger, so it just looked a bit wrong (especially next to my maxx running 7" tires at half the wheelbase). I saw these a few days ago, and ordered a pair to check them out. Very excited. Apparently they can be made to fit on normal 40 series beadlocks, and that pushes the diameter up to 10.5-11" from what I've read on other forums. The attached picture I believe is a FG monsterbeetle I found on a forum.

RE: Custom 1/5 Scale Monster Build Report

Tires came in, attached are pics of them versus redcat rampage MT tires. they're also up against my beater emaxx (with 2" extension and MOAB tires for size reference).

these guys are big for sure, the foams are a bit soft but I may stuff some firmer 40 series foams under them before I throw them on rims to fix them up.

You can also spot a few more machiend parts in there. The pinion for the bevel drive for the differentials. 12DP 16T to 32T, these are some BIG beefy gears. No issues with failure here.

With the change in tire size, I upped the wheelbase to 26". Gotta stay definiively the biggest ;).

I purchased the motor(s) for this guy last year, well before the mamba system came out (in hindsight I probably would've done that). I'll keep it under wraps for a bit (until the gearbox is assembled and running), but I'll just say it will be packing substantially more power than the mamba or any of the 22xx series nuemotrs.

RE: Custom 1/5 Scale Monster Build Report

I'm digging the machined gears. That's something I never did, although I "know" how. I used the quotes because reading about and watching it be done is totally different than setting it up and cutting yourself. You should record and post some vid of the parts being cut. I'm sure the gearheads here would enjoy it.

RE: Custom 1/5 Scale Monster Build Report

Quote:

You should record and post some vid of the parts being cut. I'm sure the gearheads here would enjoy it.

*nods*

RE: Custom 1/5 Scale Monster Build Report

Quote:

ORIGINAL: willclark77

I'm digging the machined gears. That's something I never did, although I "know" how.I used the quotes becausereading about and watching it be done is totally different than setting it up and cutting yourself. You should record and post some vid of the parts being cut. I'm sure the gearheads here would enjoy it.

The gear teeth themself weren't cut, the pinion and spur are just heavily modified (massive weight reduction) off the shelf Martin gears. 12DP i some big teeth though, and since the pinion ins 16T (1.25" pitch) and the spur is 32T (2.5" spur), they've much stronger than what is traditionally done (an incredibly tiny pinion).

RE: Custom 1/5 Scale Monster Build Report

Picked up the roughcut suspension arms today.

They currently are ust the 2d profile, I will be bolting them to a large plate and doing the holes on my manual mill (that's what the funky looking hoops are for).

The lower arms are .625" nylatron, the upper are .375" 6061.

Both will attach to ball ends to the wheelknuckles. The upper will be attaching with an intermediate turnbuckle to adjust camber.

The lower arms look a bit ugly to me, as I had a few competing design priorities. The person cutting them really wanted the number of pierces (closed loops/holes) reduced to save cut time, and I wanted to retain the ability to attach teh shocks just about everywhere so I can run this car in just about any setup. Obviously it's built as a big and heavy monster truck basher, but I'd like to be able to run it on road. I also am not 100% sure my planned method for shocks will work (dual LST shocks per wheel), so I needed to be able to switch to other types down the road.

In about 24.5 huors, I'll be done with school and working for the summer, so expect a LOT more progress then! I plan to get this badass backflipping this summer.

-

I never really stated a summary of the project, so I'll fill you guys in on most of what i have planned, but haven't pictured.

Overall Design:
I guess you could describe this as a true 1:5 scale savage flux, but it didn't start out this way. I am a mechanical engineering student who does a lot of competitive robot design work, so this really isn't my primary element (although I love rc cars!). I did a lot of resarch, and went through many, many iterations of this guy in Solidworks. What i ended up with was not intended to be a copy of the savage, but nearly everyone who sees it goes, "whoa, that looks *just* like a big savege". I guess HPI just has the best engineers ;).

Design Goals:
I wanted to build a true 1:5 scale, or larger, monster truck that could take some serious abuse. My inspiration for a durability standard was the savage flux and it's standing double backflips. If this thing can't do at least a single standing backflip, I will almost consider it a failure. Not only do I want it to have that ability, but I want the entire geartrain to standup to that kind of abuse day after day. This is not a small feat, and I havea few ideas about what might fail the first time around, but I'll get it there some day.

Electronics:
Haven't decided on a radio yet.
Servos, dual BMS-530 @6V. combined 48 kg-cm of torque, I fear it might not be enough, but they really were the all around best value per dollar for superhightorque.
Motors, <a target="_blank" href="http://www.okhobby.com/product.php?id_product=1164">dual infinite c5496 1320kv brushless motors.
</a>ESC, <a target="_blank" href="http://www.okhobby.com/product.php?id_product=1136">dual infinite 120A esc
</a>In hindsight, I would have gone with teh new mamba xl system, but i purchased these on preorder for $180 a pair esc/motor last summer. If failure occours, I'll be switching to the mamba setup.
I'll also be running this through an arduino to give myself some higher level options in terms of sensors (might try to do some basic automation like traction control), and ability to control LEDs, etc...

Suspension:
dual LST shocks per corner, got them damn cheap on ebay!
camber and toe-in adjustment via turnbuckles.
Designed to have zero bump steer, and to maintain camber angle during suspension travel.
Sway bar similar to the 5b/t setup.
Lower arms will have a LOT of shock mounting holes
Shocktowers will be screw adjustable so unbolting the shocks will not be necessary on the top end. Fine adjustment can be made just by turning a screw.

Frame/Body
TVP design very similar to savege, spaced apart with a lot of .375" nylatron crossmembers for a damn strong I-beam.
Roll cage that is shock mounted w/ rubber dampeners to reduce the stress of it landing on it's roof.
Body totally undecided on at this point. I wish someone made a stadium truck body in 1:5 scale, but I may end up just going with a 5t body.

DriveLine
Custom single speed dual motor gearbox w/ slipper clutch. All 20DP .375" thick gears.
no brake currently, going to try the electrical brake first. Have the option to add it.
Completely custom u-joint shafts all around w/ sliding hexes.
the front and rear diffs are baja 5t diffs w/ an adpater to mount the custom bevel gears to them.
No center diff currently, might possibly add later on using another baja diff. Center diff kinds of ruins the backflips.

Wheels
Plan to run those demolishers now.
a set of redcat rampge MT tires as well, for when the ridiculous diameter of the demolishers isn't necessary.
I'd like to get a set of four of the 5b rear paddle tires for the sand dunes near here.
I'd also like to get a set of four of the 5b rear hostile slicks for the street.

Power:
I will be running a 2s2p setup of 4s/5s 20C 5AH turnigy packs. I have a set of 4 each already. that works out to 8s and 10s ~ 10Ah. Surpsigingly, this was substantially cheaper than any single 5-6AH pack that would still source the current, this will also give me some awesome runtimes i'm hoping. When those wear out I'll switch to Life packs likely.

RE: Custom 1/5 Scale Monster Build Report

Hello this is a project that I'll follow closely! I want to do something like this, butwithout being monstertruck, I want to use 8-inch wheels andin the end I wantthis tolook like a buggy this isto give more control and stability to the car. I'll also use dual brushless 1090kv leopard 5692, 150A esc with two 6s lipo batteries connected in parallel.

One of my problems are the gears, I can not find anything that is cheap and strong ... I'll leave here a picture of what I intend to do and it may serve you to get some idea!

http://i271.photobucket.com/albums/j...itledLarge.jpg

http://i271.photobucket.com/albums/j...irecoLarge.jpg

RE: Custom 1/5 Scale Monster Build Report

Quote:

ORIGINAL: corsamegane

Hello this is a project that I'll follow closely! I want to do something like this, butwithout being monstertruck, I want to use 8-inch wheels andin the end I wantthis tolook like a buggy this isto give more control and stability to the car. I'll also use dual brushless 1090kv leopard 5692, 150A esc with two 6s lipo batteries connected in parallel.

One of my problems are the gears, I can not find anything that is cheap and strong ... I'll leave here a picture of what I intend to do and it may serve you to get some idea!

<div></div><div>It really depends on what your resources are.</div><div></div><div>I've got a manul mill and lathe in our shop, and a huge surplus and variety of 20DP gears (more or less the standard for what the team does). So it's trivial for us, and at a low cost.</div><div>
If you have no machining available, that's a different predicament.</div><div>
Are you just wanting to do the initial spur reduction custom? or the bevel setup as well? What resources do you have for fabrication?
</div>

RE: Custom 1/5 Scale Monster Build Report

man do i hate it when people hijack a thread to show off what they are also working on.....[&o]

RE: Custom 1/5 Scale Monster Build Report

Quote:

One of my problems are the gears, I can not find anything that is cheap and strong ...

Angle grinder gears are good, but maybe a bit heavy for what you're doing?
Most 4 inch grinders have a ratio around 3.5:1 - 4:1.

Also look at cordless drills for planetary gear setups.
Cheaper ones might have plastic gears but I've pulled apart plenty that have metal gears.

http://www.thecordlesstoolstore.info...ary%20gear.jpg

Quote:

man do i hate it when people hijack a thread to show off what they are also working on.....

This is a forum where people help eachother and ask for advice.
We're all trying to do the same thing - build cars from scratch and using whatever is available.

Sharing ideas and inspiring eachother.

What DOES suck is people who come out of nowhere and complain about stuff for no reason.
[&o]

RE: Custom 1/5 Scale Monster Build Report

Quote:

Angle grinder gears are good, but maybe a bit heavy for what you're doing?
Most 4 inch grinders have a ratio around 3.5:1 - 4:1.

They probably wouldn't be too big, My spur gears are 50T 20dp 3/8" thick, thats a .5 lb steel gear before pocketing. For the bevels, the 36T 12DP gears are absolutely massive.

We're talking about 10+ horsepower going through here, there needs to be some beef in those gears. If anything, I'd rather have this thing weight a few ounces more than stripping gear.

RE: Custom 1/5 Scale Monster Build Report

No no... that was in response to Corsamegane.
;)

RE: Custom 1/5 Scale Monster Build Report

thats why people should start there own thread!!!! then we dont get confusion over all this!!! 1 build 1 thread.....

RE: Custom 1/5 Scale Monster Build Report

Sorry, remind me again how you're contributing to this thread?

RE: Custom 1/5 Scale Monster Build Report

Why don't you both start a new thread and argue there ;)

With school done, I'm cleaning up the CAD a bit before I commit to really start cranking out parts. I'm already dissatisifed with the chassis pictured for a few reasons, and am putting the finishing touches on rev2 today. I'll post some screens tonight.

RE: Custom 1/5 Scale Monster Build Report

Meh I'll just ignore him from now on.

Look forward to the pics mate.
This is an interesting build.

RE: Custom 1/5 Scale Monster Build Report

I'm really unhappy with this picture, but I said I'd throw a pic up.

This CAD is pretty awful for my usual standards (you'll even notice a lot of things backwards!), but I threw it together real quick to show an idea of how this bad boy is going to look.

This chassis shown is still a work in progress, and I'm not that happy with it's shape. I added a few inches of wheelbase, and made it possible to remove the entire front/rear bulkhead assembly with arms etc... without having to dissasemble the chassis.

It's looking like the weight is going to come in around 40 lbs w/ body, but that's also with 6 lbs in lipos and ~11 lbs in tires. If I bought more ex*****ve lipos that could source more current, I could shave some weight off.

You'll probably start to notice with me that almost all of this is machined, nothing done by hand. That really comes down to me not being great with my hands! I admire all the guys on here that can just "throw some stuff together" with a hacksaw, but that's just not me. I'm not half bad at design, but i'm certainly no hand craftsman (which is why I love machines).

I also attached a picture of my other hobby, so you guys can get an idea of what I'm usually working with!

RE: Custom 1/5 Scale Monster Build Report

I miss FIRST Robotics :(

RE: Custom 1/5 Scale Monster Build Report

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all the guys on here that can just "throw some stuff together"

Speaking as someone who throws stuff together, I admire/envy you guys who have access to hi tech gear and the skills to use them.
So it all evens out.

;)

RE: Custom 1/5 Scale Monster Build Report

those bulkheads were machined at a comunity college

FYI

Has anyone tried the Muggy shocks compared to LST?

RE: Custom 1/5 Scale Monster Build Report

Quote:

ORIGINAL: borisdamole

those bulkheads were machined at a comunity college

FYI

Has anyone tried the Muggy shocks compared to LST?

lol, is that you taylor?

RE: Custom 1/5 Scale Monster Build Report

did you really not know? its my usual SN..... lol